A digital recording and reproducing apparatus of A & V encodes an audio signal and a video signal into digital data, then rearranges a time-sequence of the data every certain amount of data, then the rearranged data is recorded into magnetic recording medium. The rearranged data is restored to original time sequence when the data is reproduced.
The rearrangement at recording and its restoring at reproducing are referred to as “shuffling” and “deshuffling.” This method is effective when parts of the data are dropped out due to scratches on the magnetic medium, because the drop-outs are not intensively gathered at one point but they are dispersed. As a result, a time of audio discontinuity due to drop-out of data can be shortened.
When data is reproduced in a reverse direction by such a conventional magnetic recording and reproducing apparatus as discussed above, audio data deshuffled is once stored in a memory, then the data is read out in a reverse order from the memory at given intervals. This is for realizing the same practice as a recording and reproducing apparatus having a linear audio track.
FIG. 3 is a block diagram of a deshuffling section of the conventional recording and reproducing apparatus.
The deshuffling section at the reproducing side shown in FIG. 3 comprises the following elements:
(a) video deshuffling circuit 4;
(b) video deshuffling address generator 5 for instructing an order of video deshuffling;
(c) audio deshuffling circuit 6;
(d) audio deshuffling address generator 7 for instructing an order of audio deshuffling;
(e) data rearranging circuit 8 for reverse reproduction; and
(f) switching circuit 9 for switching a signal responsive to data-reproduction-direction-signal 10.
Deshuffling circuit 4 and address generator 5 constitutes a video deshuffling section.
An output data from deshuffling circuit 6 is stored in a built-in memory of data rearranging circuit 8. Circuit 6 reads the data at given intervals from the built-in memory in a reverse order to the storing order.
When the data is reproduced in a normal direction (reproduction in a positive direction), switching circuit 9 is closed to contact 9a side, and output data is supplied from audio deshuffling circuit 6 as audio data. When the data is reproduced in a reverse direction, circuit 9 is closed to contact 9b side, and output data is supplied from data rearranging circuit 8 as audio data.
The conventional method discussed above requires the data rearranging circuit having the built-in memory in order to rearrange the deshuffled audio data to reverse order when the data is reproduced in a reverse direction. As a result, this structure increases the cost. Further the deshuffled audio data should be stored in a given period for rearrangement. On the other hand, deshuffled video data does not require the rearranging circuit. Therefore, the audio data is delayed with respect to the video data for a certain period due to the rearrangement. In general, this certain period often corresponds to one frame of video data. Thus reproduction timings of video data and audio data do not agree upon each other.